feat(office): mail preview, infinite scroll, pane resize, and scrollbars

Polish the office TUI with proportional pane layout, drag resize, live
filtering, HTML mail preview, paginated mail lists, overflow scrollbars,
flattened navigation, and project save/status fixes; add UpdateProjectStatus.

Co-authored-by: Cursor <cursoragent@cursor.com>

cmd/office/fetch/calendar.go

@@ -0,0 +1,53 @@
+package fetch
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/eslider/go-onlyoffice/cmd/office/model"
+)
+
+// CalendarItemFields maps calendar API rows to list items.
+var CalendarItemFields = FieldMap{IDKey: "objectId", TitleKey: "title"}
+
+// CalendarItemsFromRows converts API calendar/event rows into list items.
+func CalendarItemsFromRows(rows []map[string]any) []model.Item {
+	out := make([]model.Item, 0, len(rows))
+	for _, row := range rows {
+		kind, typeLabel := model.ClassifyCalendarRow(row)
+		title := str(row, "title")
+		if title == "" {
+			title = str(row, "name")
+		}
+		if title == "" {
+			title = "(untitled)"
+		}
+		raw := make(map[string]any, len(row)+1)
+		for k, v := range row {
+			raw[k] = v
+		}
+		raw["type"] = typeLabel
+		out = append(out, model.Item{
+			ID:    idStr(row, "objectId"),
+			Title: title,
+			Kind:  kind,
+			Raw:   raw,
+		})
+	}
+	return out
+}
+
+// ListCalendar returns calendars and events for the upcoming date window.
+func (l *Loader) ListCalendar(ctx context.Context) ([]model.Item, error) {
+	if l == nil || l.Client == nil {
+		return nil, fmt.Errorf("fetch: client is nil")
+	}
+	start := time.Now().AddDate(0, 0, -7).Format("2006-01-02")
+	end := time.Now().AddDate(0, 0, 30).Format("2006-01-02")
+	rows, err := l.Client.ListCalendars(ctx, start, end)
+	if err != nil {
+		return nil, err
+	}
+	return CalendarItemsFromRows(rows), nil
+}